Control architecture for output torque shaping and motor torque determination for a hybrid powertrain system

ABSTRACT

A powertrain system includes a transmission device operative to transfer power between an input member and a plurality of torque machines and an output member. The torque machines are connected to an energy storage device and the transmission device is operative in one of a plurality of operating range states. A method for controlling the powertrain system includes monitoring available power from the energy storage device, determining system constraints, determining constraints on an output torque to the output member based upon the system constraints and the available power from the energy storage device, determining an operator torque request, determining an output torque command based upon the constraints on the output torque and the operator torque request, and determining preferred torque commands for each of the torque machines based upon the output torque command.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/985,243 filed on Nov. 4, 2007 which is hereby incorporated herein byreference.

TECHNICAL FIELD

This disclosure pertains to control systems for hybrid powertrainsystems.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Known hybrid powertrain architectures can include multipletorque-generative devices, including internal combustion engines andnon-combustion machines, e.g., electric machines, which can transmittorque to an output member preferably through a transmission device. Oneexemplary hybrid powertrain includes a two-mode, compound-split,electromechanical transmission which utilizes an input member forreceiving tractive torque from a prime mover power source, preferably aninternal combustion engine, and an output member. The output member canbe operatively connected to a driveline for a motor vehicle fortransmitting tractive torque thereto. Torque machines, e.g., electricmachines operative as motors or generators, can generate torque inputsto the transmission independently of a torque input from the internalcombustion engine. The torque machines may transform vehicle kineticenergy transmitted through the vehicle driveline to energy that isstorable in an energy storage device. A control system monitors variousinputs from the vehicle and the operator and provides operationalcontrol of the hybrid powertrain, including controlling transmissionoperating state and gear shifting, controlling the torque-generativedevices, and regulating the power interchange among the energy storagedevice and the machines to manage outputs of the transmission, includingtorque and rotational speed.

SUMMARY

A powertrain system includes a transmission device operative to transferpower between an input member and a plurality of torque machines and anoutput member. The torque machines are connected to an energy storagedevice and the transmission device is operative in one of a plurality ofoperating range states. A method for controlling the powertrain systemincludes monitoring available power from the energy storage device,determining system constraints, determining constraints on an outputtorque to the output member based upon the system constraints and theavailable power from the energy storage device, determining an operatortorque request, determining an output torque command based upon theconstraints on the output torque and the operator torque request, anddetermining preferred torque commands for each of the torque machinesbased upon the output torque command.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an exemplary hybrid powertrain, inaccordance with the present disclosure;

FIG. 2 is a schematic diagram of an exemplary architecture for a controlsystem and hybrid powertrain, in accordance with the present disclosure;and

FIGS. 3-7 are schematic flow diagrams of a control system architecturefor controlling and managing torque in a hybrid powertrain system, inaccordance with the present disclosure.

DETAILED DESCRIPTION

Referring now to the drawings, wherein the showings are for the purposeof illustrating certain exemplary embodiments only and not for thepurpose of limiting the same, FIGS. 1 and 2 depict an exemplary hybridpowertrain. The exemplary hybrid powertrain in accordance with thepresent disclosure is depicted in FIG. 1, comprising a two-mode,compound-split, electromechanical hybrid transmission 10 operativelyconnected to an engine 14 and torque machines comprising first andsecond electric machines (‘MG-A’) 56 and (‘MG-B’) 72. The engine 14 andfirst and second electric machines 56 and 72 each generate mechanicalpower which can be transferred to the transmission 10. The powergenerated by the engine 14 and the first and second electric machines 56and 72 and transferred to the transmission 10 is described in terms ofinput and motor torques, referred to herein as T_(I), T_(A), and T_(B)respectively, and speed, referred to herein as N_(I), N_(A), and N_(B),respectively.

The exemplary engine 14 comprises a multi-cylinder internal combustionengine selectively operative in several states to transfer torque to thetransmission 10 via an input shaft 12, and can be either aspark-ignition or a compression-ignition engine. The engine 14 includesa crankshaft (not shown) operatively coupled to the input shaft 12 ofthe transmission 10. A rotational speed sensor 11 monitors rotationalspeed of the input shaft 12. Power output from the engine 14, comprisingrotational speed and engine torque, can differ from the input speedN_(I) and the input torque T_(I) to the transmission 10 due to placementof torque-consuming components on the input shaft 12 between the engine14 and the transmission 10, e.g., a hydraulic pump (not shown) and/or atorque management device (not shown).

The exemplary transmission 10 comprises three planetary-gear sets 24, 26and 28, and four selectively engageable torque-transferring devices,i.e., clutches C1 70, C2 62, C3 73, and C4 75. As used herein, clutchesrefer to any type of friction torque transfer device including single orcompound plate clutches or packs, band clutches, and brakes, forexample. A hydraulic control circuit (‘HYD’) 42, preferably controlledby a transmission control module (hereafter ‘TCM’) 17, is operative tocontrol clutch states. Clutches C2 62 and C4 75 preferably comprisehydraulically-applied rotating friction clutches. Clutches C1 70 and C373 preferably comprise hydraulically-controlled stationary devices thatcan be selectively grounded to a transmission case 68. Each of theclutches C1 70, C2 62, C3 73, and C4 75 is preferably hydraulicallyapplied, selectively receiving pressurized hydraulic fluid via thehydraulic control circuit 42.

The first and second electric machines 56 and 72 preferably comprisethree-phase AC machines, each including a stator (not shown) and a rotor(not shown), and respective resolvers 80 and 82. The motor stator foreach machine is grounded to an outer portion of the transmission case68, and includes a stator core with coiled electrical windings extendingtherefrom. The rotor for the first electric machine 56 is supported on ahub plate gear that is operatively attached to shaft 60 via the secondplanetary gear set 26. The rotor for the second electric machine 72 isfixedly attached to a sleeve shaft hub 66.

Each of the resolvers 80 and 82 preferably comprises a variablereluctance device including a resolver stator (not shown) and a resolverrotor (not shown). The resolvers 80 and 82 are appropriately positionedand assembled on respective ones of the first and second electricmachines 56 and 72. Stators of respective ones of the resolvers 80 and82 are operatively connected to one of the stators for the first andsecond electric machines 56 and 72. The resolver rotors are operativelyconnected to the rotor for the corresponding first and second electricmachines 56 and 72. Each of the resolvers 80 and 82 is signally andoperatively connected to a transmission power inverter control module(hereafter ‘TPIM’) 19, and each senses and monitors rotational positionof the resolver rotor relative to the resolver stator, thus monitoringrotational position of respective ones of first and second electricmachines 56 and 72. Additionally, the signals output from the resolvers80 and 82 are interpreted to provide the rotational speeds for first andsecond electric machines 56 and 72, i.e., N_(A) and N_(B), respectively.

The transmission 10 includes an output member 64, e.g. a shaft, which isoperably connected to a driveline 90 for a vehicle (not shown), toprovide output power to the driveline 90 that is transferred to vehiclewheels 93, one of which is shown in FIG. 1. The output power at theoutput member 64 is characterized in terms of an output rotational speedN_(O) and an output torque T_(O). A transmission output speed sensor 84monitors rotational speed and rotational direction of the output member64. Each of the vehicle wheels 93 is preferably equipped with a sensor94 adapted to monitor wheel speed, the output of which is monitored by acontrol module of a distributed control module system described withrespect to FIG. 2, to determine vehicle speed, and absolute and relativewheel speeds for braking control, traction control, and vehicleacceleration management.

The input torque from the engine 14 and the motor torques from the firstand second electric machines 56 and 72 (T_(I), T_(A), and T_(B)respectively) are generated as a result of energy conversion from fuelor electrical potential stored in an electrical energy storage device(hereafter ‘ESD’) 74. The ESD 74 is high voltage DC-coupled to the TPIM19 via DC transfer conductors 27. The transfer conductors 27 include acontactor switch 38. When the contactor switch 38 is closed, undernormal operation, electric current can flow between the ESD 74 and theTPIM 19. When the contactor switch 38 is opened electric current flowbetween the ESD 74 and the TPIM 19 is interrupted. The TPIM 19 transmitselectrical power to and from the first electric machine 56 by transferconductors 29, and the TPIM 19 similarly transmits electrical power toand from the second electric machine 72 by transfer conductors 31 tomeet the torque commands for the first and second electric machines 56and 72 in response to the motor torque commands T_(A) and T_(B).Electrical current is transmitted to and from the ESD 74 in accordancewith whether the ESD 74 is being charged or discharged.

The TPIM 19 includes the pair of power inverters (not shown) andrespective motor control modules (not shown) configured to receive themotor torque commands and control inverter states therefrom forproviding motor drive or regeneration functionality to meet thecommanded motor torques T_(A) and T_(B). The power inverters compriseknown complementary three-phase power electronics devices, and eachincludes a plurality of insulated gate bipolar transistors (not shown)for converting DC power from the ESD 74 to AC power for poweringrespective ones of the first and second electric machines 56 and 72, byswitching at high frequencies. The insulated gate bipolar transistorsform a switch mode power supply configured to receive control commands.There is typically one pair of insulated gate bipolar transistors foreach phase of each of the three-phase electric machines. States of theinsulated gate bipolar transistors are controlled to provide motor drivemechanical power generation or electric power regenerationfunctionality. The three-phase inverters receive or supply DC electricpower via DC transfer conductors 27 and transform it to or fromthree-phase AC power, which is conducted to or from the first and secondelectric machines 56 and 72 for operation as motors or generators viatransfer conductors 29 and 31 respectively.

FIG. 2 is a schematic block diagram of the distributed control modulesystem. The elements described hereinafter comprise a subset of anoverall vehicle control architecture, and provide coordinated systemcontrol of the exemplary hybrid powertrain described in FIG. 1. Thedistributed control module system synthesizes pertinent information andinputs, and executes algorithms to control various actuators to achievecontrol objectives, including objectives related to fuel economy,emissions, performance, drivability, and protection of hardware,including batteries of ESD 74 and the first and second electric machines56 and 72. The distributed control module system includes an enginecontrol module (hereafter ‘ECM’) 23, the TCM 17, a battery pack controlmodule (hereafter ‘BPCM’) 21, a brake control module (hereafter ‘BrCM’)22, and the TPIM 19. A hybrid control module (hereafter ‘HCP’) 5provides supervisory control and coordination of the ECM 23, the TCM 17,the BPCM 21, the BrCM 22 and the TPIM 19. A user interface (‘UI’) 13 isoperatively connected to a plurality of devices through which a vehicleoperator controls or directs operation of the electromechanical hybridpowertrain. The devices include an accelerator pedal 113 (‘AP’) fromwhich an operator torque request is determined, an operator brake pedal112 (‘BP’), a transmission gear selector 114 (‘PRNDL’), and a vehiclespeed cruise control (not shown). The transmission gear selector 114 mayhave a discrete number of operator-selectable positions, including therotational direction of the output member 64 to enable one of a forwardand a reverse direction.

The aforementioned control modules communicate with other controlmodules, sensors, and actuators via a local area network (hereafter‘LAN’) bus 6. The LAN bus 6 allows for structured communication ofstates of operating parameters and actuator command signals between thevarious control modules. The specific communication protocol utilized isapplication-specific. The LAN bus 6 and appropriate protocols providefor robust messaging and multi-control module interfacing between theaforementioned control modules, and other control modules providingfunctionality including e.g., antilock braking, traction control, andvehicle stability. Multiple communications buses may be used to improvecommunications speed and provide some level of signal redundancy andintegrity. Communication between individual control modules can also beeffected using a direct link, e.g., a serial peripheral interface(‘SPI’) bus (not shown).

The HCP 5 provides supervisory control of the hybrid powertrain, servingto coordinate operation of the ECM 23, TCM 17, TPIM 19, and BPCM 21.Based upon various input signals from the user interface 13 and thehybrid powertrain, including the ESD 74, the HCP 5 determines variouscommands, including: the operator torque request, an output torquecommand (‘To cmd’) to the driveline 90, an engine input torque command,clutch torque(s) (‘TCL’) for the torque-transfer clutches C1 70, C2 62,C3 73, C4 75 of the transmission 10; and the torque commands T_(A) andT_(B) for the first and second electric machines 56 and 72. The TCM 17is operatively connected to the hydraulic control circuit 42 andprovides various functions including monitoring various pressure sensingdevices (not shown) and generating and communicating control signals tovarious solenoids (not shown) thereby controlling pressure switches andcontrol valves contained within the hydraulic control circuit 42.

The ECM 23 is operatively connected to the engine 14, and functions toacquire data from sensors and control actuators of the engine 14 over aplurality of discrete lines, shown for simplicity as an aggregatebi-directional interface cable 35. The ECM 23 receives the engine inputtorque command from the HCP 5. The ECM 23 determines the actual engineinput torque, T_(I), provided to the transmission 10 at that point intime based upon monitored engine speed and load, which is communicatedto the HCP 5. The ECM 23 monitors input from the rotational speed sensor11 to determine the engine input speed to the input shaft 12, whichtranslates to the transmission input speed, N_(I). The ECM 23 monitorsinputs from sensors (not shown) to determine states of other engineoperating parameters including, e.g., a manifold pressure, enginecoolant temperature, ambient air temperature, and ambient pressure. Theengine load can be determined, for example, from the manifold pressure,or alternatively, from monitoring operator input to the acceleratorpedal 113. The ECM 23 generates and communicates command signals tocontrol engine actuators, including, e.g., fuel injectors, ignitionmodules, and throttle control modules, none of which are shown.

The TCM 17 is operatively connected to the transmission 10 and monitorsinputs from sensors (not shown) to determine states of transmissionoperating parameters. The TCM 17 generates and communicates commandsignals to control the transmission 10, including controlling thehydraulic control circuit 42. Inputs from the TCM 17 to the HCP 5include estimated clutch torques for each of the clutches, i.e., C1 70,C2 62, C3 73, and C4 75, and rotational output speed, NO, of the outputmember 64. Other actuators and sensors may be used to provide additionalinformation from the TCM 17 to the HCP 5 for control purposes. The TCM17 monitors inputs from pressure switches (not shown) and selectivelyactuates pressure control solenoids (not shown) and shift solenoids (notshown) of the hydraulic control circuit 42 to selectively actuate thevarious clutches C1 70, C2 62, C3 73, and C4 75 to achieve varioustransmission operating range states, as described hereinbelow.

The BPCM 21 is signally connected to sensors (not shown) to monitor theESD 74, including states of electrical current and voltage parameters,to provide information indicative of parametric states of the batteriesof the ESD 74 to the HCP 5. The parametric states of the batteriespreferably include battery state-of-charge, battery voltage, batterytemperature, and available battery power, referred to as a range P_(BAT)_(—) _(MIN) to P_(BAT) _(—) _(MAX).

A brake control module (hereafter ‘BrCM’) 22 is operatively connected tofriction brakes (not shown) on each of the vehicle wheels 93. The BrCM22 monitors the operator input to the brake pedal 112 and generatescontrol signals to control the friction brakes and sends a controlsignal to the HCP 5 to operate the first and second electric machines 56and 72 based thereon.

Each of the control modules ECM 23, TCM 17, TPIM 19, BPCM 21, and BrCM22 is preferably a general-purpose digital computer comprising amicroprocessor or central processing unit, storage mediums comprisingread only memory (‘ROM’), random access memory (‘RAM’), electricallyprogrammable read only memory (‘EPROM’), a high speed clock, analog todigital (‘A/D’) and digital to analog (‘D/A’) circuitry, andinput/output circuitry and devices (‘I/O’) and appropriate signalconditioning and buffer circuitry. Each of the control modules has a setof control algorithms, comprising resident program instructions andcalibrations stored in one of the storage mediums and executed toprovide the respective functions of each computer. Information transferbetween the control modules is preferably accomplished using the LAN bus6 and SPI buses. The control algorithms are executed during preset loopcycles such that each algorithm is executed at least once each loopcycle. Algorithms stored in the non-volatile memory devices are executedby one of the central processing units to monitor inputs from thesensing devices and execute control and diagnostic routines to controloperation of the actuators, using preset calibrations. Loop cycles areexecuted at regular intervals, for example each 3.125, 6.25, 12.5, 25and 100 milliseconds during ongoing operation of the hybrid powertrain.Alternatively, algorithms may be executed in response to the occurrenceof an event.

The exemplary hybrid powertrain selectively operates in one of severalstates that can be described in terms of engine states comprising one ofan engine-on state (‘ON’) and an engine-off state (‘OFF’), andtransmission operating range states comprising a plurality of fixedgears and continuously variable operating modes, described withreference to Table 1, below.

TABLE 1 Engine Transmission Operating Applied Description State RangeState Clutches M1_Eng_Off OFF EVT Mode 1 C1 70 M1_Eng_On ON EVT Mode 1C1 70 G1 ON Fixed Gear Ratio 1 C1 70 C4 75 G2 ON Fixed Gear Ratio 2 C170 C2 62 M2_Eng_Off OFF EVT Mode 2 C2 62 M2_Eng_On ON EVT Mode 2 C2 62G3 ON Fixed Gear Ratio 3 C2 62 C4 75 G4 ON Fixed Gear Ratio 4 C2 62 C373 Neutral ON Neutral — —

Each of the transmission operating range states is described in thetable and indicates which of the specific clutches C1 70, C2 62, C3 73,and C4 75 are applied for each of the operating range states. A firstcontinuously variable mode, i.e., EVT Mode 1, or M1, is selected byapplying clutch C1 70 only in order to “ground” the outer gear member ofthe third planetary gear set 28. The engine state can be one of ON(‘M1_Eng_On’) or OFF (‘M1_Eng_Off’). A second continuously variablemode, i.e., EVT Mode 2, or M2, is selected by applying clutch C2 62 onlyto connect the shaft 60 to the carrier of the third planetary gear set28. The engine state can be one of ON (‘M2_Eng_On’) or OFF(‘M2_Eng_Off’). For purposes of this description, when the engine stateis OFF, the engine input speed is equal to zero revolutions per minute(‘RPM’), i.e., the engine crankshaft is not rotating. A fixed gearoperation provides a fixed ratio operation of input-to-output speed ofthe transmission 10, i.e., N_(I)/N_(O). A first fixed gear operation(‘G1’) is selected by applying clutches C1 70 and C4 75. A second fixedgear operation (‘G2’) is selected by applying clutches C1 70 and C2 62.A third fixed gear operation (‘G3’) is selected by applying clutches C262 and C4 75. A fourth fixed gear operation (‘G4’) is selected byapplying clutches C2 62 and C3 73. The fixed ratio operation ofinput-to-output speed increases with increased fixed gear operation dueto decreased gear ratios in the planetary gears 24, 26, and 28. Therotational speeds of the first and second electric machines 56 and 72,N_(A) and N_(B) respectively, are dependent on internal rotation of themechanism as defined by the clutching and are proportional to the inputspeed measured at the input shaft 12.

In response to operator input via the accelerator pedal 113 and brakepedal 112 as captured by the user interface 13, the HCP 5 and one ormore of the other control modules determine torque commands to controlthe torque actuators to meet the operator torque request at the outputmember 64 for transference to the driveline 90. The torque actuatorspreferably include torque generative devices, e.g., the engine 14 andtorque machines comprising the first and second electric machines 56 and72 in this embodiment. The torque actuators preferably further include atorque transferring device, comprising the transmission 10 in thisembodiment. Based upon input signals from the user interface 13 and thehybrid powertrain including the ESD 74, the HCP 5 determines theoperator torque request, a commanded output torque from the transmission10 to the driveline 90, an input torque from the engine 14, clutchtorques for the torque-transfer clutches C1 70, C2 62, C3 73, C4 75 ofthe transmission 10; and the motor torques for the first and secondelectric machines 56 and 72, respectively, as is described hereinbelow.

Final vehicle acceleration can be affected by other factors including,e.g., road load, road grade, and vehicle mass. The engine state and thetransmission operating range state are determined based upon operatingcharacteristics of the hybrid powertrain. This includes the operatortorque request communicated through the accelerator pedal 113 and brakepedal 112 to the user interface 13 as previously described. Thetransmission operating range state and the engine state may bepredicated on a hybrid powertrain torque demand caused by a command tooperate the first and second electric machines 56 and 72 in anelectrical energy generating mode or in a torque generating mode. Thetransmission operating range state and the engine state can bedetermined by an optimization algorithm or routine which determinesoptimum system efficiency based upon operator demand for power, batterystate of charge, and energy efficiencies of the engine 14 and the firstand second electric machines 56 and 72. The control system managestorque inputs from the engine 14 and the first and second electricmachines 56 and 72 based upon an outcome of the executed optimizationroutine, and system efficiencies are optimized thereby, to manage fueleconomy and battery charging. Furthermore, operation can be determinedbased upon a fault in a component or system. The HCP 5 monitors thetorque-generative devices, and determines the power output from thetransmission 10 at output member 64 that is required to meet theoperator torque request while meeting other powertrain operatingdemands, e.g., charging the ESD 74. As should be apparent from thedescription above, the ESD 74 and the first and second electric machines56 and 72 are electrically-operatively coupled for power flowtherebetween. Furthermore, the engine 14, the first and second electricmachines 56 and 72, and the electromechanical transmission 10 aremechanically-operatively coupled to transfer power therebetween togenerate a power flow to the output member 64.

FIG. 3 shows a control system architecture for controlling and managingsignal flow in a hybrid powertrain system having multiple torquegenerative devices, described hereinbelow with reference to the hybridpowertrain system of FIGS. 1 and 2, and residing in the aforementionedcontrol modules in the form of executable algorithms and calibrations.The control system architecture is applicable to alternative hybridpowertrain systems having multiple torque generative devices, including,e.g., a hybrid powertrain system having an engine and a single electricmachine, a hybrid powertrain system having an engine and multipleelectric machines. Alternatively, the hybrid powertrain system canutilize non-electric torque machines and energy storage systems, e.g.,hydraulic-mechanical hybrid transmissions using hydraulically poweredtorque machines (not shown).

In operation, the operator inputs to the accelerator pedal 113 and thebrake pedal 112 are monitored to determine the operator torque request.The operator inputs to the accelerator pedal 113 and the brake pedal 112comprise individually determinable operator torque request inputsincluding an immediate accelerator output torque request (‘Output TorqueRequest Accel Immed’), a predicted accelerator output torque request(‘Output Torque Request Accel Prdtd’), an immediate brake output torquerequest (‘Output Torque Request Brake Immed’), a predicted brake outputtorque request (‘Output Torque Request Brake Prdtd’) and an axle torqueresponse type (‘Axle Torque Response Type’). As used herein, the term‘accelerator’ refers to an operator request for forward propulsionpreferably resulting in increasing vehicle speed over the presentvehicle speed, when the operator selected position of the transmissiongear selector 114 commands operation of the vehicle in the forwarddirection. The terms ‘deceleration’ and ‘brake’ refer to an operatorrequest preferably resulting in decreasing vehicle speed from thepresent vehicle speed. The immediate accelerator output torque request,the predicted accelerator output torque request, the immediate brakeoutput torque request, the predicted brake output torque request, andthe axle torque response type are individual inputs to the controlsystem. Additionally, operation of the engine 14 and the transmission 10are monitored to determine the input speed (‘Ni’) and the output speed(‘No’).

The immediate accelerator output torque request comprises an immediatetorque request determined based upon the operator input to theaccelerator pedal 113. The control system controls the output torquefrom the hybrid powertrain system in response to the immediateaccelerator output torque request to cause positive acceleration of thevehicle. The immediate brake output torque request comprises animmediate braking request determined based upon the operator input tothe brake pedal 112. The control system controls the output torque fromthe hybrid powertrain system in response to the immediate brake outputtorque request to cause deceleration, or negative acceleration, of thevehicle. Vehicle deceleration effected by control of the output torquefrom the hybrid powertrain system is combined with vehicle decelerationeffected by a vehicle braking system (not shown) to decelerate thevehicle to achieve the immediate braking request.

The immediate accelerator output torque request is determined based upona presently occurring operator input to the accelerator pedal 113, andcomprises a request to generate an immediate output torque at the outputmember 64 preferably to accelerate the vehicle. The immediateaccelerator output torque request is unshaped, but can be shaped byevents that affect vehicle operation outside the powertrain control.Such events include vehicle level interruptions in the powertraincontrol for antilock braking, traction control and vehicle stabilitycontrol, which can be used to unshape or rate-limit the immediateaccelerator output torque request.

The predicted accelerator output torque request is determined based uponthe operator input to the accelerator pedal 113 and comprises an optimumor preferred output torque at the output member 64. The predictedaccelerator output torque request is preferably equal to the immediateaccelerator output torque request during normal operating conditions,e.g., when any one of antilock braking, traction control, or vehiclestability is not being commanded. When any one of antilock braking,traction control or vehicle stability is being commanded the predictedaccelerator output torque request remains the preferred output torquewith the immediate accelerator output torque request being decreased inresponse to output torque commands related to the antilock braking,traction control, or vehicle stability control.

The immediate brake output torque request is determined based upon theoperator input to the brake pedal 112 and the control signal to controlthe friction brakes to generate friction braking torque.

The predicted brake output torque request comprises an optimum orpreferred brake output torque at the output member 64 in response to anoperator input to the brake pedal 112 subject to a maximum brake outputtorque generated at the output member 64 allowable regardless of theoperator input to the brake pedal 112. In one embodiment the maximumbrake output torque generated at the output member 64 is limited to −0.2g. The predicted brake output torque request can be phased out to zerowhen vehicle speed approaches zero regardless of the operator input tothe brake pedal 112. As desired by a user, there can be operatingconditions under which the predicted brake output torque request is setto zero, e.g., when the operator setting to the transmission gearselector 114 is set to a reverse gear, and when a transfer case (notshown) is set to a four-wheel drive low range. The operating conditionswhereat the predicted brake output torque request is set to zero arethose in which blended braking is not preferred due to vehicle operatingfactors.

The axle torque response type comprises an input state for shaping andrate-limiting the output torque response through the first and secondelectric machines 56 and 72. The input state for the axle torqueresponse type can be an active state, preferably comprising one of apleasability limited state a maximum range state, and an inactive state.When the commanded axle torque response type is the active state, theoutput torque command is the immediate output torque. Preferably thetorque response for this response type is as fast as possible.

Blended brake torque includes a combination of the friction brakingtorque generated at the wheels 93 and the output torque generated at theoutput member 64 which reacts with the driveline 90 to decelerate thevehicle in response to the operator input to the brake pedal 112. TheBrCM 22 commands the friction brakes on the wheels 93 to apply brakingforce and generates a command for the transmission 10 to create anegative output torque which reacts with the driveline 90 in response tothe immediate braking request. Preferably the applied braking force andthe negative output torque can decelerate and stop the vehicle so longas they are sufficient to overcome vehicle kinetic power at wheel(s) 93.The negative output torque reacts with the driveline 90, thustransferring torque to the electromechanical transmission 10 and theengine 14. The negative output torque reacted through theelectromechanical transmission 10 can be transferred to the first andsecond electric machines 56 and 72 to generate electric power forstorage in the ESD 74.

A strategic optimization control scheme (‘Strategic Control’) 310determines a preferred input speed (‘Ni_Des’) and a preferred enginestate and transmission operating range state (‘Hybrid Range State Des’)based upon the output speed and the operator torque request and basedupon other operating parameters of the hybrid powertrain, includingbattery power limits and response limits of the engine 14, thetransmission 10, and the first and second electric machines 56 and 72.The predicted accelerator output torque request and the predicted brakeoutput torque request are input to the strategic optimization controlscheme 310. The strategic optimization control scheme 310 is preferablyexecuted by the HCP 5 during each 100 ms loop cycle and each 25 ms loopcycle. The desired operating range state for the transmission 10 and thedesired input speed from the engine 14 to the transmission 10 are inputsto the shift execution and engine start/stop control scheme 320.

The shift execution and engine start/stop control scheme 320 commandschanges in the transmission operation (‘Transmission Commands’)including changing the operating range state based upon the inputs andoperation of the powertrain system. This includes commanding executionof a change in the transmission operating range state if the preferredoperating range state is different from the present operating rangestate by commanding changes in application of one or more of theclutches C1 70, C2 62, C3 73, and C4 75 and other transmission commands.The present operating range state (‘Hybrid Range State Actual’) and aninput speed profile (‘Ni_Prof’) can be determined. The input speedprofile is an estimate of an upcoming input speed and preferablycomprises a scalar parametric value that is a targeted input speed forthe forthcoming loop cycle.

A tactical control scheme (‘Tactical Control and Operation’) 330 isrepeatedly executed during one of the control loop cycles to determineengine commands (‘Engine Commands’) for operating the engine 14,including a preferred input torque from the engine 14 to thetransmission 10 based upon the output speed, the input speed, and theoperator torque request comprising the immediate accelerator outputtorque request, the predicted accelerator output torque request, theimmediate brake output torque request, the predicted brake output torquerequest, the axle torque response type, and the present operating rangestate for the transmission. The engine commands also include enginestates including one of an all-cylinder operating state and a cylinderdeactivation operating state wherein a portion of the engine cylindersare deactivated and unfueled, and engine states including one of afueled state and a fuel cutoff state. An engine command comprising thepreferred input torque of the engine 14 and a present input torque(‘Ti’) reacting between the engine 14 and the input member 12 arepreferably determined in the ECM 23. Clutch torques (‘Tcl’) for each ofthe clutches C1 70, C2 62, C3 73, and C4 75, including the presentlyapplied clutches and the non-applied clutches are estimated, preferablyin the TCM 17.

An output and motor torque determination scheme (‘Output and MotorTorque Determination’) 340 is executed to determine the preferred outputtorque from the powertrain (‘To_cmd’). This includes determining motortorque commands (‘T_(A)’, ‘T_(B)’) to transfer a net commanded outputtorque to the output member 64 of the transmission 10 that meets theoperator torque request, by controlling the first and second electricmachines 56 and 72 in this embodiment. The immediate accelerator outputtorque request, the immediate brake output torque request, the presentinput torque from the engine 14 and the estimated applied clutchtorque(s), the present operating range state of the transmission 10, theinput speed, the input speed profile, and the axle torque response typeare inputs. The output and motor torque determination scheme 340executes to determine the motor torque commands during each iteration ofone of the loop cycles. The output and motor torque determination scheme340 includes algorithmic code which is regularly executed during the6.25 ms and 12.5 ms loop cycles to determine the preferred motor torquecommands.

The hybrid powertrain is controlled to transfer the output torque to theoutput member 64 to react with the driveline 90 to generate tractivetorque at wheel(s) 93 to forwardly propel the vehicle in response to theoperator input to the accelerator pedal 113 when the operator selectedposition of the transmission gear selector 114 commands operation of thevehicle in the forward direction. Similarly, the hybrid powertrain iscontrolled to transfer the output torque to the output member 64 toreact with the driveline 90 to generate tractive torque at wheel(s) 93to propel the vehicle in a reverse direction in response to the operatorinput to the accelerator pedal 113 when the operator selected positionof the transmission gear selector 114 commands operation of the vehiclein the reverse direction. Preferably, propelling the vehicle results invehicle acceleration so long as the output torque is sufficient toovercome external loads on the vehicle, e.g., due to road grade,aerodynamic loads, and other loads.

FIG. 4 details signal flow for the output and motor torque determinationscheme 340 for controlling and managing the output torque through thefirst and second electric machines 56 and 72, described with referenceto the hybrid powertrain system of FIGS. 1 and 2 and the control systemarchitecture of FIG. 3. The output and motor torque determination scheme340 controls the motor torque commands of the first and second electricmachines 56 and 72 to transfer a net output torque to the output member64 of the transmission 10 that reacts with the driveline 90 and meetsthe operator torque request, subject to constraints and shaping. Theoutput and motor torque determination scheme 340 preferably includesalgorithmic code and predetermined calibration code which is regularlyexecuted during the 6.25 ms and 12.5 ms loop cycles to determinepreferred motor torque commands (‘T_(A)’, ‘T_(B)’) for controlling thefirst and second electric machines 56 and 72 in this embodiment.

The output and motor torque determination scheme 340 determines and usesa plurality of inputs to determine constraints on the output torque,from which it determines the output torque command (‘To_cmd’). The motortorque commands (‘T_(A)’, ‘T_(B)’) for the first and second electricmachines 56 and 72 can be determined based upon the output torquecommand. The inputs to the output and motor torque determination scheme340 include operator inputs, powertrain system inputs and constraints,and autonomic control inputs.

The operator inputs include the immediate accelerator output torquerequest (‘Output Torque Request Accel Immed’) and the immediate brakeoutput torque request (‘Output Torque Request Brake Immed’).

The autonomic control inputs include torque offsets to effect activedamping of the driveline 90 (412), to effect engine pulse cancellation(408), and to effect a closed loop correction based upon the input andclutch slip speeds (410). The torque offsets for the first and secondelectric machines 56 and 72 to effect active damping of the driveline 90can be determined (‘Ta AD’, ‘Tb AD’), e.g., to manage and effectdriveline lash adjustment, and are output from an active dampingalgorithm (‘AD’) (412). The torque offsets to effect engine pulsecancellation (‘Ta PC’, ‘Tb PC’) are determined during starting andstopping of the engine during transitions between the engine-on state(‘ON’) and the engine-off state (‘OFF’) to cancel engine torquedisturbances, and are output from a pulse cancellation algorithm (‘PC’)(408). The torque offsets for the first and second electric machines 56and 72 to effect closed-loop correction torque are determined bymonitoring input speed to the transmission 10 and clutch slip speeds ofclutches C1 70, C2 62, C3 73, and C4 75. The closed-loop correctiontorque offsets for the first and second electric machines 56 and 72 (‘TaCL’, ‘Tb CL’) can be determined based upon an input speed error, i.e., adifference between the input speed from sensor 11 (‘Ni’) and the inputspeed profile (‘Ni_Prof’) and a clutch slip speed error, i.e., adifference between clutch slip speed and a targeted clutch slip speed,e.g., a clutch slip speed profile for a targeted clutch C1 70. Whenoperating in one of the mode operating range states, the closed-loopcorrection torque offsets for the first and second electric machines 56and 72 (‘Ta CL’, ‘Tb CL’) can be determined primarily based upon theinput speed error. When operating in Neutral, the closed-loop correctionis based upon the input speed error and the clutch slip speed error fora targeted clutch, e.g., C1 70. The closed-loop correction torqueoffsets are output from a closed loop control algorithm (‘CL’) (410).The clutch slip speeds of the non-applied clutches can be determined forthe specific operating range state based upon motor speeds for the firstand second electric machines 56 and 72 and the speed of the outputmember 64. The targeted clutch slip speed and clutch slip profile arepreferably used during a transition in the operating range state of thetransmission to synchronize clutch slip speed prior to applying anoncoming clutch. The closed-loop motor torque offsets and the motortorque offsets to effect active damping of the driveline 90 are input toa low pass filter (‘LPF’) 405 to determine filtered motor torquecorrections for the first and second electric machines 56 and 72 (‘TaLPF’ and Tb LPF’).

The powertrain system inputs and constraints include maximum and minimumavailable battery power limits (‘P_(BAT) Min/Max’) output from a batterypower limit algorithm (‘P BAT’) (466), the operating range state(‘Hybrid Range State’), and a plurality of system inputs and constraints(‘System Inputs and Constraints’). The system inputs can include scalarparameters specific to the powertrain system and the operating rangestate, and can be related to speed and acceleration of the input member12, output member 64, and the clutches. Other system inputs are relatedto system inertias, damping, and electric/mechanical power conversionefficiencies in this embodiment. The constraints include maximum andminimum motor torque outputs from the torque machines, i.e., first andsecond electric machines 56 and 72 and maximum and minimum clutchreactive torques for the applied clutches. Other system inputs includethe input torque, clutch slip speeds and other relevant states.

Inputs including an input acceleration profile (‘Nidot_Prof’) and aclutch slip acceleration profile (“Clutch Slip Accel Prof’) are input toa pre-optimization algorithm (415), along with the system inputs, theoperating range state, and the motor torque corrections for the firstand second electric machines 56 and 72 (‘Ta LPF’ and Tb LPF’). The inputacceleration profile is an estimate of an upcoming input accelerationthat preferably comprises a targeted input acceleration for theforthcoming loop cycle. The clutch slip acceleration profile is anestimate of upcoming clutch acceleration for one or more of thenon-applied clutches, and preferably comprises a targeted clutch slipacceleration for the forthcoming loop cycle. Optimization inputs (‘OptInputs’), which can include values for motor torques, clutch torques andoutput torques can be calculated for the present operating range stateand used in an optimization algorithm (440). The optimization algorithm(440) is preferably executed to determine the maximum and minimum rawoutput torque constraints (440) and to determine the preferred split ofopen-loop torque commands between the first and second electric machines56 and 72 (440’). The optimization inputs, the maximum and minimumbattery power limits, the system inputs and the present operating rangestate are analyzed to determine a preferred or optimum output torque(‘To Opt’) and minimum and maximum raw output torque constraints (‘ToMin Raw’, ‘To Max Raw’) which can be shaped and filtered (420). Thepreferred output torque (‘To Opt’) comprises an output torque thatminimizes battery power subject to a range of net output torques thatare less than the immediate accelerator output torque request. Thepreferred output torque comprises the net output torque that is lessthan the immediate accelerator output torque request and yields theminimum battery power subject to the output torque constraints. Theimmediate accelerator output torque request and the immediate brakeoutput torque request are each shaped and filtered and subjected to theminimum and maximum output torque constraints (‘To Min Filt’, ‘To MaxFilt’) to determine minimum and maximum filtered output torque requestconstraints (‘To Min Req Filt’, ‘To Max Req Filt’). A constrainedaccelerator output torque request (‘To Req Accel Cnstrnd’) and aconstrained brake output torque request (‘To Req Brake Cnstrnd’) can bedetermined based upon the minimum and maximum filtered output torquerequest constraints (425).

Furthermore, a regenerative braking capacity (‘Opt Regen Capacity’) ofthe transmission 10 comprises a capacity of the transmission 10 to reactdriveline torque, and can be determined based upon constraints includingmaximum and minimum motor torque outputs from the torque machines andmaximum and minimum reactive torques for the applied clutches, takinginto account the battery power limits. The regenerative braking capacityestablishes a maximum value for the immediate brake output torquerequest. The regenerative braking capacity is determined based upon adifference between the constrained accelerator output torque request andthe preferred output torque (‘To Opt’). The constrained acceleratoroutput torque request is shaped and filtered and combined with aconstrained, shaped, and filtered brake output torque request todetermine a net output torque command. The net output torque command iscompared to the minimum and maximum request filtered output torques todetermine the output torque command (‘To_cmd’) (430). When the netoutput torque command is between the maximum and minimum requestfiltered output torques, the output torque command is set to the netoutput torque command. When the net output torque command exceeds themaximum request filtered output torque, the output torque command is setto the maximum request filtered output torque. When the net outputtorque command is less than the minimum request filtered output torque,the output torque command is set to the minimum request filtered outputtorque command.

Powertrain operation is monitored and combined with the output torquecommand to determine a preferred split of open-loop torque commandsbetween the first and second electric machines 56 and 72 that meetsreactive clutch torque capacities (‘Ta Opt’ and ‘Tb Opt’), and providefeedback related to the preferred battery power (‘Pbat Opt’) (440’). Themotor torque corrections for the first and second electric machines 56and 72 (‘Ta LPF’ and Tb LPF’) are subtracted to determine open loopmotor torque commands (‘Ta OL’ and ‘Tb OL’) (460).

The open loop motor torque commands are combined with the autonomiccontrol inputs including the torque offsets to effect active damping ofthe driveline 90 (412), to effect engine pulse cancellation (408), andto effect a closed loop correction based upon the input and clutch slipspeeds (410), to determine the motor torques T_(A) and T_(B) forcontrolling the first and second electric machines 56 and 72 (470). Theaforementioned steps of constraining, shaping and filtering the outputtorque request to determine the output torque command which is convertedinto the torque commands for the first and second electric machines 56and 72 is preferably a feed-forward operation which acts upon the inputsand uses algorithmic code to calculate the torque commands.

The system operation as configured leads to determining output torqueconstraints based upon present operation and constraints of thepowertrain system. The operator torque request is determined based uponoperator inputs to the brake pedal and to the accelerator pedal. Theoperator torque request can be constrained, shaped and filtered todetermine the output torque command, including determining a preferredregenerative braking capacity. An output torque command can bedetermined that is constrained based upon the constraints and theoperator torque request. The output torque command is implemented bycommanding operation of the torque machines. The system operationeffects powertrain operation that is responsive to the operator torquerequest and within system constraints. The system operation results inan output torque shaped with reference to operator driveability demands,including smooth operation during regenerative braking operation.

The optimization algorithm (440, 440’) comprises an algorithm executedto determine powertrain system control parameters that are responsive tothe operator torque request that minimizes battery power consumption.The optimization algorithm (440, 440’) includes monitoring presentoperating conditions of the electromechanical hybrid powertrain, e.g.,the powertrain system described hereinabove, based upon the systeminputs and constraints, the present operating range state, and theavailable battery power limits. For a candidate input torque, theoptimization algorithm (440, 440’) calculates powertrain system outputsthat are responsive to the system inputs comprising the aforementionedoutput torque commands and are within the maximum and minimum motortorque outputs from the first and second electric machines 56 and 72,and within the available battery power, and within the range of clutchreactive torques from the applied clutches for the present operatingrange state of the transmission 10, and take into account the systeminertias, damping, clutch slippages, and electric/mechanical powerconversion efficiencies. Preferably, the powertrain system outputsinclude the preferred output torque (‘To Opt’), achievable torqueoutputs from the first and second electric machines 56 and 72 (‘Ta Opt’,‘Tb Opt’) and the preferred battery power (‘Pbat Opt’) associated withthe achievable torque outputs.

FIGS. 5, 6, and 7 show the optimization algorithm (440, 440’), whichincludes monitoring present operating conditions of theelectro-mechanical hybrid powertrain, e.g., the powertrain systemdescribed hereinabove. Offset motor torques for the first and secondelectric machines 56 and 72 can be calculated based upon inputsincluding the operating range state (‘ORS’) of the transmission 10, theinput torque (‘T_(I)’) and other terms based upon system inertias,system damping, and clutch slippage (510).

FIG. 6 graphically shows an operating region for an exemplary powertrainsystem, including determining linear torque constraints to the outputtorque (520) to determine a region of allowable motor torques for thefirst and second electric machines 56 and 72 in this embodiment. Thegraph in FIG. 6 shows motor torque constraints (‘Motor TorqueConstraints’) comprising minimum and maximum achievable motor torquesfor the first and second electric machines 56 and 72, and depicted inFIG. 5 (‘T_(A)Min’, ‘T_(A)Max’, ‘T_(B)Min’, and ‘T_(B)Max’). Minimum andmaximum clutch reactive torques for applied clutch(es) CL1 and CL2 aregraphed relative to the motor torque constraints, for first and, asshown (where necessary), second applied clutches (‘T_(CL1) MIN’,‘T_(CL1) MAX’) and (‘T_(CL2) MIN’, ‘T_(CL2) MAX’), also depicted in FIG.5 (‘T_(CLn)Min’, ‘T_(CLn)Max’). Minimum and maximum linear outputtorques (‘To Min Lin’, ‘To Max Lin’) can be determined based upon theoffset motor torques, the minimum and maximum achievable motor torquesfor the first and second electric machines 56 and 72 and the minimum andmaximum clutch reactive torques for the applied clutch(es). The minimumand maximum linear output torques are the minimum and maximum outputtorques that meet the motor torque constraints and also meet the appliedclutch torque constraints. In the example shown, the minimum and maximumclutch reactive torques for the second applied clutch CL2 are lessrestrictive and outside the motor torque constraints, and thus do notconstrain the output torque. Operation is bounded by the region definedby the minimum and maximum clutch reactive torques for the first appliedclutch CL1 and the minimum and maximum motor torque constraints for thesecond electric machine 72 (‘T_(B)Min’ and ‘T_(B)Max’). The maximumlinear output torque is the maximum output torque in this region, i.e.,the output torque at the intersection between the maximum motor torqueconstraint for the second electric machine 72 (‘T_(B)Max’) and minimumclutch reactive torque for the first applied clutch (‘T_(CL1) Min’). Theminimum linear output torque is the minimum output torque in thisregion, i.e., the output torque at the intersection between the minimummotor torque command for the second electric machine 72 (‘Tb Min’) andmaximum clutch reactive torque for the first applied clutch (‘T_(CL1)Max’).

FIG. 7 graphically shows battery power (P_(BAT)) plotted against outputtorque (‘T_(O)’) having a (0, 0) point designated by letter M, for anexemplary system. The graph as depicted can be used to determine anunconstrained quadratic solution, which includes an optimized outputtorque (‘To*’) and an optimized battery power (‘P_(BAT)*’) for operatingthe system with no other system constraints (530). The power for theenergy storage device 74 can be represented mathematically as a functionof the transmission output torque To as shown below:

P _(BAT)(T _(O))=(a ₁ ² +b ₁ ²)(T_(O) −T _(O)*)² +P _(BAT)*   [1]

where a₁ and b₁ represent scalar values determined for the specificapplication. Eq. 1 can be solved for the output torque, as shown below.

$\begin{matrix}{{T_{O}\left( P_{BAT} \right)} = {T_{O}^{*} \pm \sqrt{\frac{P_{BAT} - P_{BAT}^{*}}{a_{1}^{2} + b_{1}^{2}}}}} & \lbrack 2\rbrack\end{matrix}$

For the available battery power range P_(BAT) _(—) _(MIN) to P_(BAT)_(—) _(MAX), four distinct output torques can be determined from Eq. 2,including maximum and minimum quadratic output torque constraints forthe positive root case (‘To@P_(BAT)Max Pos’ and ‘To@P_(BAT)Min Pos’),and minimum and maximum quadratic output torque constraints for thenegative root case (‘To@P_(BAT)Max Neg’ and ‘To@P_(BAT)Min Neg’),plotted with reference to FIG. 7. FIG. 7 shows valid, achievable rangesfor the output torque based upon the battery power.

The preferred output torque (‘To Opt’) can be determined based upon theoptimized output torque (‘To*’), the optimized battery power(‘P_(BAT)*’), the maximum and minimum linear torque output, and theoutput torque search range (‘To Search Range’). The output torque searchrange (‘To Search Range’) preferably comprises the immediate acceleratoroutput torque request when the optimization algorithm is executed todetermine the maximum and minimum raw output torque constraints (440).This includes selecting a temporary output torque comprising a minimumtorque value of the search range for the output torque and the maximumoutput torque. The output torque search range (‘To Search Range’)preferably comprises the output torque command (‘To_cmd’) when theoptimization algorithm is used to determine the preferred split ofopen-loop torque commands between the first and second electric machines56 and 72 (440’).

The preferred output torque (‘To Opt’) is selected as the maximum of thetemporary output torque, the minimum output torque determined based uponone of the quadratic output torque constraints and clutch torqueconstraints, and the minimum linear output torque (540). Output torqueconstraints including minimum and maximum unfiltered output torques (‘ToMin Raw’, ‘To Max Raw’) are determined based upon inputs including acapability of the powertrain to transmit and convert electric power tomechanical torque through the first and second electric machines 56 and72 (‘Ta Min/Max’, ‘Tb Min/Max’) and the immediate or present torque,speed, and electric power inputs thereto. The preferred output torque(‘To Opt’) is determined based upon inputs including the immediateaccelerator output torque request.

The preferred output torque (‘To Opt’) is subject to output torqueconstraints comprising the minimum and maximum unfiltered output torques(‘To Min Raw’, ‘To Max Raw’) and is determined based upon the range ofallowable output torques, which can vary, and may include the immediateaccelerator output torque request. The preferred output torque maycomprise an output torque corresponding to a minimum battery dischargepower or an output torque corresponding to a maximum battery chargepower. The preferred output torque is based upon a capacity of thepowertrain to transmit and convert electric power to mechanical torquethrough the first and second electric machines 56 and 72, and theimmediate or present torque, speed, and reactive clutch torqueconstraints, and electric power inputs thereto. The output torqueconstraints including the minimum and maximum unfiltered output torques(‘To Min Raw’, ‘To Max Raw’) and the preferred output torque (‘To Opt’)can be determined by executing and solving an optimization function inone of the operating range states for neutral, mode and fixed gearoperation. The optimization function 440 comprises a plurality of linearequations implemented in an executable algorithm and solved duringongoing operation of the system to determine the preferred output torquerange to minimize battery power consumption and meet the operator torquerequest. Each of the linear equations takes into account the inputtorque (‘Ti’), system inertias and linear damping. Preferably, there arelinear equations specific to each of the operating range states forneutral, mode and fixed gear operations, described with reference toEqs. 3-10, below.

The output torque constraints comprise a preferred output torque rangeat the present input torque, within the available battery power(‘P_(BAT) Min/Max’) and within the motor torque constraints subject tothe reactive clutch torques of the applied torque transfer clutches. Theoutput torque request is constrained within maximum and minimum outputtorque capacities. In fixed gear and mode operation, the preferredoutput torque can comprise the output torque which maximizes charging ofthe ESD 74. In neutral, the preferred output torque is calculated. Infixed gear operation, the preferred output torque can include thepreferred torque split between the first and second electric machines 56and 72 while meeting the reactive clutch torque constraints.

Preferred motor torques and battery powers (‘T_(A) Opt’, ‘T_(B) Opt’,and ‘P_(BAT) Opt’) can be determined based upon the preferred outputtorque, and used to control operation of the powertrain system. Thepreferred motor torques comprise motor torques which minimize power flowfrom the ESD 74 and achieve the preferred output torque. Torque outputsfrom the first and second electric machines 56 and 72 are controlledbased upon the determined minimum power flow from the battery, which isthe preferred battery power (‘P_(BAT) Opt’). Torque output is controlledbased upon the engine input torque and the torque commands for the firstand second electric machines 56 and 72, (‘T_(A) Opt’, ‘T_(B) Opt’)respectively, which minimizes the power flow from the ESD 74 to meet thepreferred output torque. The battery powers associated with the motors(‘P_(A) Opt’ and ‘P_(B) Opt’, respectively) can be determined based uponthe torque commands (560). Linear equations for the operating rangestates for neutral, mode and fixed gear operations are now described.When the transmission 14 is in the neutral operating range state thelinear equation system is Eq. 3 as set forth below:

$\begin{matrix}{\begin{bmatrix}T_{A} \\T_{B} \\T_{O}\end{bmatrix} = {{\begin{bmatrix}{a\; 1} \\{a\; 2} \\{a\; 3}\end{bmatrix}T_{I}} + {\quad{{\left\lbrack \begin{matrix}{a\; 11} & {a\; 12} & {a\; 13} \\{a\; 21} & {a\; 22} & {a\; 23} \\{a\; 31} & {a\; 32} & {a\; 33}\end{matrix} \right\rbrack*\left\lbrack \begin{matrix}{Nidot} \\{Nodot} \\{Ncdot}\end{matrix} \right\rbrack} + {\left\lbrack \begin{matrix}{b\; 11} & {b\; 12} & {b\; 13} \\{b\; 21} & {b\; 22} & {b\; 23} \\{b\; 31} & {b\; 32} & {b\; 33}\end{matrix} \right\rbrack*\left\lbrack \begin{matrix}N_{I} \\N_{O} \\N_{C}\end{matrix} \right\rbrack} + {\quad{\left\lbrack \begin{matrix}{c\; 11} & {c\; 12} & {c\; 13} & {c\; 14} \\{c\; 21} & {c\; 22} & {c\; 23} & {c\; 24} \\{c\; 31} & {c\; 32} & {c\; 33} & {c\; 34} \\{c\; 41} & {c\; 41} & {c\; 43} & {c\; 44}\end{matrix} \right\rbrack*\left\lbrack \begin{matrix}{{Tcs}\; 1} \\{{Tcs}\; 2} \\{{Tcs}\; 3} \\{{Tcs}\; 4}\end{matrix} \right\rbrack}}}}}} & \lbrack 3\rbrack\end{matrix}$

The term

$\begin{bmatrix}{a\; 1} \\{a\; 2} \\{a\; 3}\end{bmatrix}T_{I}$

represents contributions to the motor torques (T_(A), T_(B)) and theoutput torque (T_(O)) due to the input torque. The ta2 and a3 terms aresystem-specific scalar values determined for the specific systemapplication.

The term

$\begin{bmatrix}{a\; 11} & {a\; 12} & {a\; 13} \\{a\; 21} & {a\; 22} & {a\; 23} \\{a\; 31} & {a\; 32} & {a\; 33}\end{bmatrix}*\begin{bmatrix}{Nidot} \\{Nodot} \\{Ncdot}\end{bmatrix}$

represents contributions to the motor torques (T_(A), T_(B)) and theoutput torque (T_(O)) due to system inertias, having three degrees offreedom.

The term

$\begin{bmatrix}{b\; 11} & {b\; 12} & {b\; 13} \\{b\; 21} & {b\; 22} & {b\; 23} \\{b\; 31} & {b\; 32} & {b\; 33}\end{bmatrix}*\begin{bmatrix}N_{I} \\N_{O} \\N_{C}\end{bmatrix}$

represents contributions to the motor torques (T_(A), T_(B)) and theoutput torque (T_(O)) due to linear damping, having three degrees offreedom. The Ni, No and Nc terms are selected as three linearlyindependent system speeds, comprising the input speed, the output speed,and clutch slip speed, which can be used to characterize the damping ofthe components of the powertrain system. And the b11-b33 terms aresystem-specific scalar values determined for the specific systemapplication.

The term

$\begin{bmatrix}{c\; 11} & {c\; 12} & {c\; 13} & {c\; 14} \\{c\; 21} & {c\; 22} & {c\; 23} & {c\; 24} \\{c\; 31} & {c\; 32} & {c\; 33} & {c\; 34} \\{c\; 41} & {c\; 41} & {c\; 43} & {c\; 44}\end{bmatrix}*\begin{bmatrix}{{Tcs}\; 1} \\{{Tcs}\; 2} \\{{Tcs}\; 3} \\{{Tcs}\; 4}\end{bmatrix}$

represents contributions to the motor torques (T_(A), T_(B)) and theoutput torque (T_(O)) due to slipping clutch torques. The Tcs1, Tcs2,Tcs3, and Tcs4 terms represent the slipping clutch torques across therespective torque transfer clutches, i.e., clutches C1 70, C2 62, C3 73,and C4 75. And, the c11-c44 terms are system-specific scalar valuesdetermined for the specific system application. One skilled in the artcan readily see application of this concept to any number of slippingclutches.

The input acceleration term, the output acceleration term, and theclutch acceleration term are selected as three linearly independentsystem accelerations which can be used to characterize the inertias ofthe components of the powertrain system. The a11-a33 terms aresystem-specific scalar values determined for the specific systemapplication.

When the transmission 14 is in one of the mode operating range statesthe linear equation for the system is Eq. 4:

$\begin{matrix}{\begin{bmatrix}T_{A} \\T_{B} \\T_{{CL}\; 1}\end{bmatrix} = {{\begin{bmatrix}k_{T_{A}{From}\mspace{11mu} T_{O}} \\k_{T_{B}{From}\mspace{11mu} T_{O}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{O}}\end{bmatrix}T_{O}} + {\quad{{\left\lbrack \begin{matrix}k_{T_{A}{From}\mspace{11mu} T_{I}} \\k_{T_{B}{From}\mspace{11mu} T_{I}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{I}}\end{matrix} \right\rbrack T_{I}} + {\left\lbrack \begin{matrix}{a\; 11} & {a\; 12} \\{a\; 21} & {a\; 22} \\{a\; 31} & {a\; 32}\end{matrix} \right\rbrack*\left\lbrack \begin{matrix}{Nidot} \\{Nodot}\end{matrix} \right\rbrack} + {\quad{{\left\lbrack \begin{matrix}{b\; 11} & {b\; 12} \\{b\; 21} & {b\; 22} \\{b\; 31} & {b\; 32}\end{matrix} \right\rbrack*\left\lbrack \begin{matrix}N_{I} \\N_{O}\end{matrix} \right\rbrack} + {\left\lbrack \begin{matrix}{c\; 11} & {c\; 12} & {c\; 13} \\{c\; 21} & {c\; 22} & {c\; 23} \\{c\; 31} & {c\; 32} & {c\; 33}\end{matrix} \right\rbrack*\begin{bmatrix}{{Tcs}\; 1} \\{{Tcs}\; 2} \\{{Tcs}\; 3}\end{bmatrix}}}}}}}} & \lbrack 4\rbrack\end{matrix}$

Eq. 4 can be solved to determine a preferred output torque whichminimizes the battery power and meets the operator torque request. TheT_(CL1) term represents reactive torque transfer across the appliedclutch for the mode operation, i.e., clutch C1 62 in Mode 1 and clutchC2 70 in Mode 2. The terms Tcs1, Tcs2, Tcs3 represent torque transferacross the non-applied, slipping clutches for the specific modeoperation.

The term

$\begin{bmatrix}k_{T_{A}{From}\mspace{11mu} T_{I}} \\k_{T_{B}{From}\mspace{11mu} T_{I}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{I}}\end{bmatrix}T_{I}$

represents contributions to the motor torques (T_(A), T_(B)) and thereactive torque transfer across the applied clutch T_(CL1) due to theinput torque T_(I). The scalar terms are based upon the torque outputsfrom the first and second electric machines 56 and 72 and the reactivetorque of the applied clutch related to the input torque(‘k_(TA from TI)’, ‘k_(TB from TI)’, ‘k_(TCL1 from TI)’) determined forthe specific system application.

The term

$\begin{bmatrix}k_{T_{A}{From}\mspace{11mu} T_{O}} \\k_{T_{B}{From}\mspace{11mu} T_{O}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{O}}\end{bmatrix}T_{O}$

represents contributions to the motor torques (T_(A), T_(B)) and thereactive torque transfer across the applied clutch T_(CL1) due to theoutput torque T_(O). The scalar terms are based upon the torque outputsfrom the first and second electric machines 56 and 72 and the reactivetorque of the applied clutch related to the input torque(‘k_(TA from To)’, ‘k_(TB from To)’, ‘k_(TCL1 from To)’) determined forthe specific system application.

The term

$\begin{bmatrix}{a\; 11} & {a\; 12} \\{a\; 21} & {a\; 22} \\{a\; 31} & {a\; 32}\end{bmatrix}*\begin{bmatrix}{Nidot} \\{Nodot}\end{bmatrix}$

represents contributions to the motor torques (T_(A), T_(B)) and thereactive torque transfer across the applied clutch T_(CL1) due to systeminertias, having two degrees of freedom. The input acceleration term andthe output acceleration term are selected as two linearly independentsystem accelerations which can be used to characterize the inertias ofthe components of the powertrain system. The a11-a32 terms aresystem-specific scalar values determined for the specific systemapplication.

The term

$\begin{bmatrix}{b\; 11} & {b\; 12} \\{b\; 21} & {b\; 22} \\{b\; 31} & {b\; 32}\end{bmatrix}*\begin{bmatrix}N_{I} \\N_{O}\end{bmatrix}$

represents contributions to the motor torques (T_(A), T_(B)) and thereactive torque transfer across the applied clutch T_(CL1) due to lineardamping, having two degrees of freedom, selected as two linearlyindependent system speeds, i.e., the input and output speeds, which canbe used to characterize the damping of the components of the powertrainsystem. The b11-b32 terms are system-specific scalar values determinedfor the specific system application.

The term

$\begin{bmatrix}{c\; 11} & {c\; 12} & {c\; 13} \\{c\; 21} & {c\; 22} & {c\; 23} \\{c\; 31} & {c\; 32} & {c\; 33}\end{bmatrix}*\begin{bmatrix}{{Tcs}\; 1} \\{{Tcs}\; 2} \\{{Tcs}\; 3}\end{bmatrix}$

represents contributions to the motor torques (T_(A), T_(B)) and thereactive torque transfer across the applied clutch T_(CL1) due tonon-applied, slipping clutch torques. The Tcs1, Tcs2, and Tcs3 termsrepresent clutch torques across the non-applied, slipping torquetransfer clutches. The c11-c33 terms are system-specific scalar valuesdetermined for the specific system application.

Eq. 4 can be rewritten as Eq. 5:

$\begin{matrix}{\begin{bmatrix}T_{A} \\T_{B} \\T_{{CL}\; 1}\end{bmatrix} = {{\begin{bmatrix}k_{T_{A}{From}\mspace{11mu} T_{O}} \\k_{T_{B}{From}\mspace{11mu} T_{O}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{O}}\end{bmatrix}T_{O}} + {\begin{bmatrix}k_{T_{A}{From}\mspace{11mu} T_{I}} \\k_{T_{B}{From}\mspace{11mu} T_{I}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{I}}\end{bmatrix}T_{I}} + \begin{bmatrix}{T_{A}{Misc}} \\{T_{A}{Misc}} \\{T_{{CL}\; 1}{Misc}}\end{bmatrix}}} & \lbrack 5\rbrack\end{matrix}$

with the offset motor torques based upon inputs including the operatingrange state of the transmission 10, the input torque and terms basedupon system inertias, system damping, and clutch slippage (‘T_(A) Misc’,‘T_(B) Misc’, ‘T_(CL1) Misc’) combined into a single vector.

For an input torque T_(I), Eq. 5 reduces to Eq. 6 as follows.

$\begin{matrix}{\begin{bmatrix}T_{A} \\T_{B} \\T_{{CL}\; 1}\end{bmatrix} = {{\begin{bmatrix}k_{T_{A}{From}\mspace{11mu} T_{O}} \\k_{T_{B}{From}\mspace{11mu} T_{O}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{O}}\end{bmatrix}T_{O}} + \begin{bmatrix}{T_{A}{Offset}} \\{T_{B}{Offset}} \\{T_{{CL}\; 1}{Offset}}\end{bmatrix}}} & \lbrack 6\rbrack\end{matrix}$

Eq. 6 can be solved using the preferred output torque (‘To Opt’) todetermine preferred motor torques from the first and second electricmachines 56 and 72 (‘T_(A) Opt’, ‘T_(B) Opt’) (550). Preferred batterypowers (‘P_(BAT)Opt’, ‘P_(A) Opt’, ‘P_(B) Opt’) can be calculated basedthereon (560).

When the transmission 14 is in one of the fixed gear operating rangestates the linear equation for the system is set forth in Eq. 7.

$\begin{matrix}{\left\lbrack \begin{matrix}T_{O} \\T_{{CL}\; 1} \\T_{{CL}\; 2}\end{matrix} \right\rbrack = {{\left\lbrack \begin{matrix}k_{T_{O}{From}\mspace{11mu} T_{A}} & k_{T_{O}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{B}}\end{matrix} \right\rbrack*\left\lbrack \begin{matrix}T_{A} \\T_{B}\end{matrix} \right\rbrack} + {\left\lbrack \begin{matrix}k_{T_{O}{From}\mspace{11mu} T_{A}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{A}} \\k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{A}}\end{matrix} \right\rbrack T_{I}} + {\begin{bmatrix}{a\; 11} \\{a\; 21} \\{a\; 31}\end{bmatrix}*N_{I}} + {\left\lbrack \begin{matrix}{b\; 11} \\{b\; 21} \\{b\; 31}\end{matrix} \right\rbrack*{Nidot}} + {\begin{bmatrix}{c\; 11} & {c\; 12} \\{c\; 21} & {c\; 22} \\{c\; 31} & {c\; 32}\end{bmatrix}*\begin{bmatrix}{{Tcs}\; 1} \\{{Tcs}\; 2}\end{bmatrix}}}} & \lbrack 7\rbrack\end{matrix}$

Eq. 7 can be solved to determine an output torque which minimizes thebattery power and meets the operator torque request. The T_(CL1) andT_(CL2) terms represent reactive torque transfer across the appliedclutches for the fixed gear operation. The terms Tcs1 and Tcs2 representtorque transfer across the non-applied, slipping clutches for thespecific fixed gear operation.

The term

$\left\lbrack \begin{matrix}k_{T_{O}{From}\mspace{11mu} T_{I}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{I}} \\k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{I}}\end{matrix} \right\rbrack*T_{I}$

represents contributions to the output torque To and the reactive torquetransfer across the applied clutches T_(CL1) and T_(CL2) due to theinput torque T_(I). The scalar terms are based upon the output torqueand the reactive torques of the applied clutches related to the inputtorque (‘k_(To from TI)’, ‘k_(TCL1 from TI)’, ‘k_(TCL2 from TI)’)determined for the specific system application.

The term

$\left\lbrack \begin{matrix}k_{T_{O}{From}\mspace{11mu} T_{A}} & k_{T_{O}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{B}}\end{matrix} \right\rbrack*\left\lbrack \begin{matrix}T_{A} \\T_{B}\end{matrix} \right\rbrack$

represents contributions to the output torques and the reactive torquetransfer across the applied clutches due to the motor torques T_(A) andT_(B). The scalar terms are based upon the output torque and thereactive torque of the applied clutches related to the torque outputsfrom the first and second electric machines 56 and 72 determined for thespecific system application.

The term

$\left\lbrack \begin{matrix}{b\; 11} \\{b\; 21} \\{b\; 31}\end{matrix} \right\rbrack*{Nidot}$

represents contributions to the output torques and the reactive torquetransfer across the applied clutches (TCL1, TCL2) due to systeminertias, having a single degree of freedom. The input acceleration termis selected as a linearly independent system acceleration which can beused to characterize the inertias of the components of the powertrainsystem. The b11 -b31 terms are system-specific scalar values determinedfor the specific system application.

The term

$\begin{bmatrix}{a\; 11} \\{a\; 21} \\{a\; 31}\end{bmatrix}*N_{I}$

represents contributions to the output torques and the reactive torquetransfer across the applied clutches T_(CL1) and T_(CL2) due to lineardamping, having a single degree of freedom, selected as a linearlyindependent system speed which can be used to characterize the dampingof the components of the powertrain system. The a11-a31 terms aresystem-specific scalar values determined for the specific systemapplication.

The term

$\begin{bmatrix}{c\; 11} & {c\; 12} \\{c\; 21} & {c\; 22} \\{c\; 31} & {c\; 32}\end{bmatrix}*\begin{bmatrix}{{Tcs}\; 1} \\{{Tcs}\; 2}\end{bmatrix}$

represents contributions to the output torque and the reactive torquetransfer across the applied clutches T_(CL1) and T_(CL2) due tonon-applied, slipping clutch torques. The Tcs1 and Tcs2 terms representclutch torques across the non-applied, slipping torque transferclutches. The c11-c32 terms are system-specific scalar values determinedfor the specific system application.

Eq. 7 can be rewritten as Eq. 8:

$\begin{matrix}{\left\lbrack \begin{matrix}T_{O} \\T_{{CL}\; 1} \\T_{{CL}\; 2}\end{matrix} \right\rbrack = {{\left\lbrack \begin{matrix}k_{T_{O}{From}\mspace{11mu} T_{A}} & k_{T_{O}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{B}}\end{matrix} \right\rbrack\left\lbrack \begin{matrix}T_{A} \\T_{B}\end{matrix} \right\rbrack} + {\left\lbrack \begin{matrix}k_{T_{O}{From}\mspace{11mu} T_{I}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{I}} \\k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{I}}\end{matrix} \right\rbrack T_{I}} + \left\lbrack \begin{matrix}k_{T_{O}{Misc}} \\k_{T_{{CL}\; 1}{Misc}} \\k_{T_{{CL}\; 2}{Misc}}\end{matrix} \right\rbrack}} & \lbrack 8\rbrack\end{matrix}$

For an input torque T_(I), Eq. 8 can be rewritten as Eq. 9:

$\begin{matrix}{\left\lbrack \begin{matrix}T_{O} \\T_{{CL}\; 1} \\T_{{CL}\; 2}\end{matrix} \right\rbrack = {{\left\lbrack \begin{matrix}k_{T_{O}{From}\mspace{11mu} T_{A}} & k_{T_{O}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 1}{From}\mspace{11mu} T_{B}} \\k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{A}} & k_{T_{{CL}\; 2}{From}\mspace{11mu} T_{B}}\end{matrix} \right\rbrack\left\lbrack \begin{matrix}T_{A} \\T_{B}\end{matrix} \right\rbrack} + \begin{bmatrix}{T_{O}{Offset}} \\{T_{{CL}\; 1}{Offset}} \\{T_{{CL}\; 2}{Offset}}\end{bmatrix}}} & \lbrack 9\rbrack\end{matrix}$

with the output torque and the reactive torque transfer across theapplied clutches T_(CL1) and T_(CL2) based upon the motor torques withthe operating range state of the transmission 10, and terms based uponinput torque, system inertias, system damping, and clutch slippage (‘ToOffset’, ‘T_(CL1) Offset’, ‘T_(CL2) _(—) Offset’) combined into a singlevector. Eq. 9 can be solved using the preferred output torque (‘To Opt’)to determine preferred motor torques from the first and second electricmachines 56 and 72, including determining preferred motor torque split(‘T_(A)Opt’, ‘T_(B)Opt’) (550).

The motor torque commands can be used to control the first and secondelectric machines 56 and 72 to transfer output torque to the outputmember 64 and thence to the driveline 90 to generate tractive torque atwheel(s) 93 to propel the vehicle in response to the operator input tothe accelerator pedal 113. Preferably, propelling the vehicle results invehicle acceleration so long as the output torque is sufficient toovercome external loads on the vehicle, e.g., due to road grade,aerodynamic loads, and other loads.

Each of Eqs. 3, 4, and 7 can be solved to determine a preferred outputtorque which minimizes the battery power and meets the operator torquerequest, and can then be executed to determine preferred motor torquesfor the first and second electric machines, subject to the clutchconstraints.

It is understood that modifications are allowable within the scope ofthe disclosure. The disclosure has been described with specificreference to the preferred embodiments and modifications thereto.Further modifications and alterations may occur to others upon readingand understanding the specification. It is intended to include all suchmodifications and alterations insofar as they come within the scope ofthe disclosure.

1. Method for controlling a powertrain system including a transmissiondevice operative to transfer power between an input member and aplurality of torque machines and an output member, the torque machinesconnected to an energy storage device and the transmission deviceoperative in one of a plurality of operating range states, the methodcomprising: monitoring available power from the energy storage device;determining system constraints; determining constraints on an outputtorque to the output member based upon the system constraints and theavailable power from the energy storage device; determining an operatortorque request; determining an output torque command based upon theconstraints on the output torque and the operator torque request; anddetermining preferred torque commands for each of the torque machinesbased upon the output torque command.
 2. The method of claim 1, furthercomprising determining the operator torque request based upon operatorinputs to an accelerator pedal and to a brake pedal.
 3. The method ofclaim 1, further comprising: determining an input acceleration profilefor the input member; and determining constraints on the output torqueto the output member based upon the input acceleration profile for theinput member, the system constraints, and the available power from theenergy storage device.
 4. The method of claim 1, comprising executing anoptimization function to determine the constraints on the output torqueto the output member based upon the system constraints and the availablepower from the energy storage device.
 5. The method of claim 4,comprising executing the optimization function for transmissionoperating range states including mode and fixed gear operation.
 6. Themethod of claim 4, comprising executing the optimization function todetermine the output torque command based upon the constraints on theoutput torque to the output member, the system constraints, and theavailable power from the energy storage device.
 7. The method of claim4, comprising executing the optimization function to determine thepreferred torque commands for each of the torque machines based upon theconstraints on the output torque to the output member, the systemconstraints, and the available power from the energy storage device. 8.Method for controlling a powertrain system including a transmissiondevice operative to transfer power between an input member and aplurality of torque machines and an output member, the torque machinesconnected to an energy storage device and the transmission deviceoperative in one of a plurality of operating range states by selectivelyapplying torque transfer clutches, the method comprising: monitoring theinput member; determining system inputs and system constraints;monitoring available power from the energy storage device; determining apresent operating range state for the transmission device; determiningconstraints on an output torque transferred to the output member basedupon the system inputs, the system constraints and the available powerfrom the energy storage device; determining an operator torque request;determining an output torque command based upon the constraints on theoutput torque and the operator torque request; and determining preferredtorque commands for each of the torque machines based upon the commandedoutput torque.
 9. The method of claim 8, further comprising: determiningan input acceleration profile for the input member and a clutch slipacceleration profile for one of the torque transfer clutches; anddetermining constraints on an output torque to the output member basedupon the input acceleration profile, the clutch slip accelerationprofile, the system constraints, and the available power from the energystorage device.
 10. The method of claim 8, further comprisingdetermining a range of output torques which react with the output memberbased upon the range of power outputs from the energy storage device,the input torque from the engine and torque transfer across theselectively applied torque transfer clutches.
 11. The method of claim 8,wherein determining the system constraints comprises determining rangesof reactive clutch torques for the selectively applied torque transferclutches.
 12. The method of claim 8, comprising executing anoptimization function to determine the constraints on the output torqueto the output member based upon the system constraints, the availablepower from the energy storage device, and the ranges of reactive clutchtorques for the selectively applied torque transfer clutches.
 13. Themethod of claim 12, comprising executing the optimization function todetermine the output torque command based upon the constraints on theoutput torque to the output member, the system constraints, theavailable power from the energy storage device, and the selectivelyapplied torque transfer clutches.
 14. The method of claim 13, comprisingexecuting the optimization function for transmission operating rangestates in one of mode and fixed gear operation.
 15. The method of claim14, comprising executing the optimization function to determine thepreferred torque commands for each of the torque machines based upon theconstraints on the output torque to the output member, the systemconstraints, and the available power from the energy storage device. 16.Method for controlling a powertrain system including anelectro-mechanical transmission device operative to transfer powerbetween an input member and first and second electric machines and anoutput member, the first and second electric machines connected to anenergy storage device and the transmission device operative in one of aplurality of operating range states by selectively applying torquetransfer clutches, the method comprising: determining motor torqueconstraints and reactive torque constraints for applied torque transferclutches; determining available power from the energy storage device;determining constraints on an output torque based upon the motor torqueconstraints, and the reactive torque constraints for the applied torquetransfer clutches and the available power from the energy storagedevice; determining an operator torque request; determining an outputtorque command based upon the constraints on the output torque and theoperator torque request; and determining preferred torque commands foreach of the torque machines based upon the commanded output torque. 17.The method of claim 16, further comprising: determining an inputacceleration profile for the input member and a clutch slip accelerationprofile for one of the torque transfer clutches; and determiningconstraints on an output torque to the output member based upon theinput acceleration profile, the clutch slip acceleration profile, themotor torque constraints and reactive torque constraints for the appliedtorque transfer clutches, and the available power from the energystorage device.
 18. The method of claim 16, comprising executing anoptimization function to determine the constraints on the output torquebased upon the motor torque constraints, the reactive torque constraintsfor applied torque transfer clutches, and the available power from theenergy storage device.
 19. The method of claim 18, comprising executingthe optimization function to determine the output torque command basedupon the constraints on the output torque, the torque commands for eachof the torque machines, the reactive torque constraints for appliedtorque transfer clutches, and the available power from the energystorage device.
 20. The method of claim 16, wherein determining theoperator torque request comprises determining an operator torque requestfor braking and determining an operator torque request for acceleration.